This invention relates generally to ski lifts and more specifically to a monitoring system applicable to any lift having detachable carrier vehicles such as chairs, gondolas or aerial tramway cars. Over the past several years, the ski and transportation industries have implemented faster and larger transportation carrier vehicles in order to move more passengers in a shorter time. Exemplary of such carrier vehicles are gondolas, trams, and high speed chairs, including quints, quads, triples, and doubles. With these high speed carrier vehicles has come the need for loading and unloading passengers in the shortest possible time. In order to satisfy this need, these carrier vehicles have become more complex mechanically. For example, almost all such high speed carrier vehicles are detachable, meaning that the carrier vehicle simply detaches from the main cable driving the lift when passengers are to be loaded or unloaded, thereby allowing the carrier vehicle to move at a much slower speed. The slower speed allows passengers to load or unload in a comfortable and safe amount of time. After the carrier vehicle has moved past a loading or unloading point, the vehicle is automatically reattached to the main cable for high speed travel to the next loading or unloading station.
With the increased mechanical complexity of these high speed carrier vehicles has come the need for increased maintenance in order to promote reliability and passenger safety. In order to properly maintain these carrier vehicles, a consistent record of their usage is necessary. Due to the fact that they can be removed from a particular lift or cable system at any time, it is essential that the usage of each carrier vehicle be accounted for separately. When one carrier vehicle requires service, it is simply removed from the cable system and replaced with another carrier vehicle. It is also common practice to vary the number of carrier vehicles in operation on a lift or cable system from day to day, depending on the anticipated passenger load. This constant shuffling of carrier vehicles between storage areas and the cable system has made it difficult, if not impossible, to accurately account for the actual usage of a given carrier vehicle.
One known method for recording the usage of carrier vehicles is a manual one that requires noting each carrier vehicle on a given cable system at the beginning of a day. At the end of the day, the total number of round trip cycles completed by the cable system is estimated and recorded for each of the vehicles on the system. Maintenance is typically scheduled for carrier vehicles based upon the number of cycles a vehicle has completed. In making a trip from the bottom of a lift to the top and then back to the bottom, the detachable grips of each vehicle must be opened and closed four times. In the case of a typical ski area, this manual recording method would require logging approximately three thousand carrier vehicles each morning. Thus, the time required to manually record the vehicle identification information is prohibitive, since the vehicles must be moved around the cable system to permit this information to be recorded. At the same time, the estimations of vehicle cycles during each day would need to be compiled for years at a time, resulting in even more paperwork and opportunity for error.
Due to the sheer volume of recorded information required under the system described above, an initial time-based system was devised for recording the required maintenance cycles of high speed chair lifts, and ski areas have never been required to keep detailed records as to the exact usage of each such carrier vehicle. However, recording of daily usage information for gondola vehicles was originally required on a daily basis since these vehicles are shuffled on and off a given cable system more frequently than are chair vehicles. This time-based system dictates that movable parts, particularly grips, be serviced on a time interval of several years. Typically, each chair is serviced in sequence and then returned to the lift. For the first several years that high speed chair lifts were in operation, this service schedule seemed to work well, and only minor safety problems arose. However, in the past few years, some chair grips have been found to be under-maintained, while others have been over-maintained. Possible explanations for this inconsistency are that some grips have received more usage than others and that manual records of service sequences have become scrambled over time. As a result, some vehicles are being overlooked, and a basically random maintenance sequence is being followed. In the more recent past, several accidents around the world have occurred due to lack of maintenance on high speed chair vehicles, thus suggesting that the time-based maintenance system requires modification to more accurately account for the usage of each vehicle.
In the case of gondolas, a manual recording system has been in daily use. In the United States, it has not been particularly difficult to record the vehicles in use on a gondola system each day because each ski area typically has no more than one such system. However, in Europe and, more recently, Japan, some ski areas have as many as twenty-four gondola systems. In these areas, the sheer volume of information to be recorded has led to adoption of the time-based system described above. Since gondola systems are arranged so that each vehicle operates at heights of 100-1000 feet above the ground, failure of a particular vehicle can be fatal. The typical gondola system includes approximately 220 carrier vehicles. At any given time, only 60 to 180 of these are in operation. The remainder are in storage or being serviced. Since the number of vehicles in actual operation varies significantly from day to day as a function of passenger traffic, it has become nearly impossible to keep track of which vehicles are on and off the cable system each day. For this reason, U.S. ski areas with gondolas are now on a time-based maintenance schedule that results in a guessing game as to which vehicles need service and which do not. Even if an accurate daily record is kept of all vehicles in operation, a slight error in estimating the number of cycles performed that day results in a large percentage error for the day, since each vehicle performs only 14-18 cycles per day. When tabulated over a time-based maintenance interval of several years, this error becomes even more significant, again regularly resulting in cases of over-maintenance and under-maintenance. Since the average service performed on each gondola vehicle is very costly, unnecessary maintenance has an adverse economic impact on the ski area, while under-maintenance jeopardizes passenger safety.
It is therefore the principal object of the present invention to provide a maintenance monitoring system for detachable carrier vehicles of a moving transportation system in which the daily operational usage of each carrier vehicle is automatically recorded and accumulated.
It is a further object of the present invention to provide a maintenance monitoring system for detachable carrier vehicles of a moving transportation system in which the accumulated usage of each carrier vehicle is compared to usage levels at which that carrier vehicle is to receive scheduled maintenance and for displaying to the user selected parameters regarding the accumulated usage of a selected one or more carrier vehicles and the relationship of that accumulated usage to the usage level at which the selected one or more carrier vehicles is to receive scheduled maintenance.
These and other objects are accomplished in accordance with the illustrated preferred embodiment of the present invention by providing a bar code, or other readable medium containing vehicle identification information, on each of the carrier vehicles of the transportation system, a stationary input unit positioned for reading the vehicle identification information from each of the carrier vehicles as the carrier vehicles pass a specified point along the route of the transportation system, a decoder for converting the vehicle identification information read by the input unit to a computer data format, and a computer system for receiving the vehicle identification information, for processing that vehicle identification information to accumulate the usage of each carrier vehicle of the transportation system, for comparing the accumulated usage of each carrier vehicle to usage levels at which that carrier vehicle is to receive scheduled maintenance, and for displaying to the user selected parameters regarding the accumulated usage of a selected one or more carrier vehicles and the relationship of that accumulated usage to the usage level at which the selected one or more carrier vehicles is to receive scheduled maintenance.